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      <title>项目中有用到多线程场景 - 交互式测验</title>
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          justify-content: space-between; /* 将按钮分布在两侧 */
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          min-height: 65px; /* Reserve space */
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          cursor: pointer;
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      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>项目中有用到多线程场景 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在处理高并发Web请求时，为什么推荐使用线程池（如 `ExecutorService`）而不是为每个请求都创建一个新线程？",
    "options": [
      "因为它能自动将同步任务转换为异步任务，提升代码可读性。",
      "因为它能保证所有请求严格按照接收顺序执行，防止数据错乱。",
      "因为它通过复用线程，避免了频繁创建和销毁线程带来的巨大性能开销。",
      "因为它占用的内存比单个线程更少，可以节省服务器资源。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "线程的创建和销毁是资源密集型操作。在高并发场景下，如果为每个请求都创建新线程，会导致系统性能急剧下降。线程池通过维护一组固定的工作线程来复用它们，从而显著减少了系统开销，提高了整体的吞吐量和响应速度。",
    "source": "文档中「1. 高并发请求处理」部分",
    "hint": "文档中提到，使用线程池是为了“避免每次请求都创建和销毁线程的开销”。"
  },
  {
    "question": "根据文档，当使用Java 8处理一个大数据集合时，哪种API可以便捷地实现并行数据处理，从而加速计算过程？",
    "options": [
      "Fork/Join框架的 `invoke()` 方法",
      "Stream API 结合 `parallelStream()` 方法",
      "`CompletableFuture` 的 `supplyAsync()` 方法",
      "`ExecutorService` 的 `submit()` 方法"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，Java 8的Stream API提供了`parallelStream()`方法，它可以非常方便地将串行流转换为并行流，利用多核处理器并行处理集合中的数据，从而简化了并行数据处理的实现并提高效率。",
    "source": "文档中「2. 并行数据处理」部分",
    "hint": "文档中提到一种可以“简化并行数据处理的实现”的Java 8 API。"
  },
  {
    "question": "如果需要在Java应用程序中实现一个每小时执行一次的数据备份定时任务，文档中提到的哪种机制是合适的选择？",
    "options": [
      "ScheduledExecutorService",
      "ForkJoinPool",
      "CompletableFuture",
      "一个普通的 ExecutorService 线程池"
    ],
    "correctAnswerIndex": 0,
    "explanation": "`ScheduledExecutorService` 是Java并发包中专门用于处理延迟任务或周期性任务的接口。它的`scheduleAtFixedRate`或`scheduleWithFixedDelay`方法非常适合实现如定时备份、数据清理等场景。",
    "source": "文档中「3. 任务调度与定时任务」部分",
    "hint": "文档中哪个示例代码展示了如何以固定的频率（`scheduleAtFixedRate`）执行任务？"
  },
  {
    "question": "在多线程环境下，当多个线程需要访问和修改同一个共享变量（如计数器）时，为避免数据不一致和竞争条件，文档中提到了哪两种主要的并发控制实现方式？",
    "options": [
      "使用消息队列和并行流（parallelStream）",
      "使用`CompletableFuture`和`Fork/Join`框架",
      "使用锁机制（如`ReentrantLock`）和原子操作（如`AtomicInteger`）",
      "使用线程池和定时任务调度器"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档在“并发控制”一节中明确列出了两种保证数据一致性的核心方法：一是使用锁机制（如`synchronized`或`ReentrantLock`）来保证代码块的互斥访问；二是使用`Atomic`原子类来进行无锁的、线程安全的操作，这在简单场景下比锁更高效。",
    "source": "文档中「4.1 数据一致性」部分",
    "hint": "回顾“并发控制”部分的两个代码示例，它们分别展示了哪两种技术？"
  },
  {
    "question": "在一个Web应用中，用户提交表单后需要执行一个耗时的操作（如发送邮件）。为了立即给用户响应并把耗时操作放到后台处理，文档推荐了哪种处理方式？",
    "options": [
      "使用 `ReentrantLock` 锁住邮件发送过程，确保其完成。",
      "使用 `Fork/Join` 框架将邮件发送任务分解成更小的部分并行执行。",
      "使用 `CompletableFuture` 或消息队列进行异步处理。",
      "使用 `parallelStream` 并行发送多封邮件。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "为了提升用户体验，应避免让用户等待耗时的后台操作。文档在“后台任务处理”部分指出，可以通过`CompletableFuture`将任务提交到后台线程池异步执行，或者将任务发送到消息队列，由独立的后台服务来消费和处理，这两种方式都能让主线程立即返回，从而快速响应用户。",
    "source": "文档中「5.1 异步任务」部分",
    "hint": "文档中提到，为了“提升用户体验”，可以将某些操作进行“异步完成”。"
  },
  {
    "question": "当需要处理如实时日志或传感器数据这类持续不断产生的数据流时，文档中推荐使用哪一类技术？",
    "options": [
      "Spring的 `@Scheduled` 注解",
      "Java的 `AtomicInteger` 类",
      "流处理框架（如 Apache Flink, Kafka Streams）",
      "Java的 `Fork/Join` 框架"
    ],
    "correctAnswerIndex": 2,
    "explanation": "对于实时、连续的数据流，批处理或简单的并行任务模型并不适用。文档在“实时数据处理”部分明确推荐使用专门的流处理框架，如Apache Flink或Kafka Streams，它们被设计用来处理和分析无界的实时数据流。",
    "source": "文档中「6. 实时数据处理」部分",
    "hint": "文档中提到了专门用于处理和分析实时数据流的“Stream Processing Frameworks”。"
  },
  {
    "question": "相较于使用`ReentrantLock`，在仅需要对一个共享的整型计数器进行线程安全的递增操作时，使用`AtomicInteger`有什么主要优势？",
    "options": [
      "`AtomicInteger`能保证操作的绝对顺序。",
      "`AtomicInteger`是基于CAS（比较并交换）的无锁操作，通常比显式加锁有更好的性能。",
      "`AtomicInteger`可以处理比`ReentrantLock`更复杂的业务逻辑。",
      "`AtomicInteger`是Java 8之后才引入的新特性。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "虽然文档中没有深入对比，但这是`Atomic`类设计的核心理念。`ReentrantLock`是一种互斥锁，会导致未能获取锁的线程被挂起，涉及上下文切换，开销较大。而`AtomicInteger`等原子类使用硬件级别的CAS指令，以一种乐观的方式尝试更新值，避免了线程阻塞，因此在低到中度竞争下，性能通常优于锁。",
    "source": "文档中「4.1 数据一致性」部分",
    "hint": "文档将原子操作和锁机制并列为两种不同的并发控制实现，思考它们在实现原理上可能存在的差异。"
  }
];
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        let score = 0;
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            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

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                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
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            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  